Pediatric health disparities in the areas of asthma and sleep persist; asthma and poor sleep outcomes are prevalent among ethnic minority and urban children. Known stressors of urban poverty and poorly controlled asthma can adversely impact the sleep health of urban children with asthma. Our work with urban children with persistent asthma has shown that Latino and African American (AA) children are exposed to sociocontextual (e.g., neighborhood stress, allergens/irritants) and cultural (e.g., acculturative stress) risks that challenge asthma management and increase asthma morbidity. Further, our recently completed study indicates real-time links among asthma, sleep quality, and daytime functioning in urban children. The roles of sleep context, daily sleep routines, and sleep behaviors of urban children of specific ethnic groups are unknown. Our work has focused on contributors to asthma health disparities, assessing sleep quality in this group with actigraphy and self-report sleep behavior measures. Cultural, sleep, and asthma-specific factors in children's sleep contexts can affect children's maintenance of healthy sleep behaviors, and in turn, asthma morbidity. Sleep timing and circadian measures have not been assessed in these groups. Targeting the sleep setting and sleep behaviors along with biological measures of underlying circadian timing in urban children with asthma has the potential to identify mechanisms to inform interventions to improve sleep and asthma outcomes. We propose to utilize a multi-method, in-depth approach to characterize the sleep patterns and sleep settings of urban children in combination with biological measures that may differ based on children's ethnic group background and may contribute to asthma outcomes. We will enroll 240 urban children (ages 7-9, from Latino, AA, and Non-Latino White backgrounds) with persistent asthma and their primary caregivers. Each child/caregiver will participate in a 16- day protocol involving an assessment of the child's sleep context, sleep status (by actigraphy; ambulatory polysomnography, PSG; saliva for dim light melatonin onset, DLMO), and asthma status (lung function by home spirometry, immune biomarker assessment, report of symptoms/control). The sleep context will be examined through our environmental walk-through assessment, in-depth caregiver/child interviews, and self-report assessments, and objective measurement of light during monitoring. The first aim of the study is to examine ethnic differences in sleep patterns, with a focus on such outcomes as timing (e.g., night-to-night variability in time to bed), continuity (e.g., nighttime arousals), and length (sleep duration) measured across 16 days with actigraphy, as well as circadian phase (DLMO) and alignment of sleep timing to circadian phase. The second aim involves examining ethnic differences in the co- occurrence of sleep status and asthma status. The third aim will identify sleep-related (e.g., sleep disruptors), asthma (e.g., availability/location of rescue medication), and cultural-related (e.g., sleep beliefs) risk and resource factors of children's sleep context that moderate associations between sleep and asthma outcomes.